论文标题
在Gaia DR2中鉴定出具有Lamost DR6和DR7光谱的热分子恒星。 ii。运动学
Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II. Kinematics
论文作者
论文摘要
通过将杆径径速度与Gaia视差和适当的运动相结合，我们提出了3D银河空间运动和182个单线热细分恒星的轨道。 Lei等人已经确定了这些恒星。 （2020）在Gaia Dr2中，Lamost DR6和DR7光谱。具有log（y）> 0的富丽的热分子恒星显示了银河速度成分和轨道参数的最大标准偏差，而具有-1 <log（y）<0的速度分量和轨道参数则显示出第二大标准偏差。具有log（y）<-1的两组缺陷型恒星显示出相似的标准偏差，与富含他的恒星相比，它在系统上更低。我们还根据它们在U-V速度图，J_z-Eccentricity图及其银河轨道中的位置，对四个热分子的氦组进行了运动种群分类。晕，薄磁盘和厚磁盘中四个热分子的氦基团的分数分布的总体趋势在很大程度上与基于Lamost DR5的Luo等人（2019）报告的结果一致，这似乎支持了二元人群合成的预测（Han等人（Han等人2003; 2003; 2008; 2008）。他缺乏-2.2 <log（y）<-1可能来自稳定的Roche Lobe溢流通道的来源，具有log（y）<-2.2的HE缺陷恒星，来自公共包膜射血通道的<-2.2，以及带有双log（y）> 0的恒星，来自双双He He He He He He He He He He He He Dwarf Stars的合并通道。在薄磁盘和光环中，具有-1 <log（y）<0的He -he He He He Hot Subdwarf恒星的比例远高于厚磁盘，这意味着这些恒星在薄磁盘和光晕中具有不同的地层通道。
Combining the LAMOST radial velocities with Gaia parallaxes and proper motions, we presented 3D Galactic space motions and the orbits of 182 single-lined hot subdwarf stars. These stars have been identified by Lei et al. (2020) in Gaia DR2 with LAMOST DR6 and DR7 spectra. He-rich hot subdwarf stars with log(y)>0 show the largest standard deviations of the Galactic velocity components and orbital parameters, while those with -1<log(y)<0 exhibit the second largest standard deviations. The two groups of He-deficient stars with log(y)<-1 show similar standard deviations, which is systematically lower compared to He-rich stars. We also presented a kinematic population classification of the four hot subdwarf helium groups based on their positions in the U-V velocity diagram, J_z-eccentricity diagram and their Galactic orbits. The overall tendency of the fractional distributions of the four hot subdwarf helium groups in the halo, thin disk and thick disk is largely consistent with the findings reported by Luo et al.(2019) based on LAMOST DR5, which appears to support the predictions of binary population synthesis (Han et al. 2003; 2008). He-deficient stars with -2.2<log(y)<-1 likely origin from stable the Roche lobe overflow channel, He-deficient stars with log(y)<-2.2 from the common envelope ejection channel, and He-rich stars with log(y)>0 from the merger channel of double He white dwarf stars. The fraction of He-rich hot subdwarf stars with -1<log(y)<0 in the thin disk and the halo are far higher than in the thick disk, which implies that these stars have different formation channels in the thin disk and in the halo.
